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/**
* @file ondemand.c
* @author Ambroz Bizjak <ambrop7@gmail.com>
*
* @section LICENSE
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the author nor the
* names of its contributors may be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* @section DESCRIPTION
*
* On-demand process manager.
*
* Synopsis:
* ondemand(string template_name, list args)
*
* Description:
* Manages an on-demand template process using a process template named
* template_name.
* On deinitialization, if the process is running, reqests its termination
* and waits for it to terminate.
*
* Synopsis:
* ondemand::demand()
*
* Description:
* Demands the availability of an on-demand template process.
* This statement is in UP state if and only if the template process of the
* corresponding ondemand object is completely up.
*
* Variables:
* Exposes variables and objects from the template process corresponding to
* the ondemand object.
*/
#include <stdlib.h>
#include <string.h>
#include <misc/offset.h>
#include <misc/debug.h>
#include <structure/LinkedList1.h>
#include <ncd/module_common.h>
#include <generated/blog_channel_ncd_ondemand.h>
struct ondemand {
NCDModuleInst *i;
NCDValRef template_name;
NCDValRef args;
LinkedList1 demands_list;
int dying;
int have_process;
NCDModuleProcess process;
int process_terminating;
int process_up;
};
struct demand {
NCDModuleInst *i;
struct ondemand *od;
LinkedList1Node demands_list_node;
};
static int ondemand_start_process (struct ondemand *o);
static void ondemand_terminate_process (struct ondemand *o);
static void ondemand_process_handler (NCDModuleProcess *process, int event);
static void ondemand_free (struct ondemand *o);
static void demand_free (struct demand *o, int is_error);
static int ondemand_start_process (struct ondemand *o)
{
ASSERT(!o->dying)
ASSERT(!o->have_process)
// start process
if (!NCDModuleProcess_InitValue(&o->process, o->i, o->template_name, o->args, ondemand_process_handler)) {
ModuleLog(o->i, BLOG_ERROR, "NCDModuleProcess_Init failed");
goto fail0;
}
// set have process
o->have_process = 1;
// set process not terminating
o->process_terminating = 0;
// set process not up
o->process_up = 0;
return 1;
fail0:
return 0;
}
static void ondemand_terminate_process (struct ondemand *o)
{
ASSERT(o->have_process)
ASSERT(!o->process_terminating)
// request termination
NCDModuleProcess_Terminate(&o->process);
// set process terminating
o->process_terminating = 1;
if (o->process_up) {
// set process down
o->process_up = 0;
// signal demands down
for (LinkedList1Node *n = LinkedList1_GetFirst(&o->demands_list); n; n = LinkedList1Node_Next(n)) {
struct demand *demand = UPPER_OBJECT(n, struct demand, demands_list_node);
ASSERT(demand->od == o)
NCDModuleInst_Backend_Down(demand->i);
}
}
}
static void ondemand_process_handler (NCDModuleProcess *process, int event)
{
struct ondemand *o = UPPER_OBJECT(process, struct ondemand, process);
ASSERT(o->have_process)
switch (event) {
case NCDMODULEPROCESS_EVENT_UP: {
ASSERT(!o->process_terminating)
ASSERT(!o->process_up)
// set process up
o->process_up = 1;
// signal demands up
for (LinkedList1Node *n = LinkedList1_GetFirst(&o->demands_list); n; n = LinkedList1Node_Next(n)) {
struct demand *demand = UPPER_OBJECT(n, struct demand, demands_list_node);
ASSERT(demand->od == o)
NCDModuleInst_Backend_Up(demand->i);
}
} break;
case NCDMODULEPROCESS_EVENT_DOWN: {
ASSERT(!o->process_terminating)
ASSERT(o->process_up)
// continue process
NCDModuleProcess_Continue(&o->process);
// set process down
o->process_up = 0;
// signal demands down
for (LinkedList1Node *n = LinkedList1_GetFirst(&o->demands_list); n; n = LinkedList1Node_Next(n)) {
struct demand *demand = UPPER_OBJECT(n, struct demand, demands_list_node);
ASSERT(demand->od == o)
NCDModuleInst_Backend_Down(demand->i);
}
} break;
case NCDMODULEPROCESS_EVENT_TERMINATED: {
ASSERT(o->process_terminating)
ASSERT(!o->process_up)
// free process
NCDModuleProcess_Free(&o->process);
// set have no process
o->have_process = 0;
// if dying, die finally
if (o->dying) {
ondemand_free(o);
return;
}
// if demands arrivied, restart process
if (!LinkedList1_IsEmpty(&o->demands_list)) {
if (!ondemand_start_process(o)) {
// error demands
while (!LinkedList1_IsEmpty(&o->demands_list)) {
struct demand *demand = UPPER_OBJECT(LinkedList1_GetFirst(&o->demands_list), struct demand, demands_list_node);
ASSERT(demand->od == o)
demand_free(demand, 1);
}
}
}
} break;
}
}
static void ondemand_func_new (void *vo, NCDModuleInst *i, const struct NCDModuleInst_new_params *params)
{
struct ondemand *o = vo;
o->i = i;
// read arguments
NCDValRef arg_template_name;
NCDValRef arg_args;
if (!NCDVal_ListRead(params->args, 2, &arg_template_name, &arg_args)) {
ModuleLog(i, BLOG_ERROR, "wrong arity");
goto fail0;
}
if (!NCDVal_IsString(arg_template_name) || !NCDVal_IsList(arg_args)) {
ModuleLog(i, BLOG_ERROR, "wrong type");
goto fail0;
}
o->template_name = arg_template_name;
o->args = arg_args;
// init demands list
LinkedList1_Init(&o->demands_list);
// set not dying
o->dying = 0;
// set have no process
o->have_process = 0;
// signal up
NCDModuleInst_Backend_Up(i);
return;
fail0:
NCDModuleInst_Backend_DeadError(i);
}
static void ondemand_free (struct ondemand *o)
{
ASSERT(!o->have_process)
// die demands
while (!LinkedList1_IsEmpty(&o->demands_list)) {
struct demand *demand = UPPER_OBJECT(LinkedList1_GetFirst(&o->demands_list), struct demand, demands_list_node);
ASSERT(demand->od == o)
demand_free(demand, 0);
}
NCDModuleInst_Backend_Dead(o->i);
}
static void ondemand_func_die (void *vo)
{
struct ondemand *o = vo;
ASSERT(!o->dying)
// if not have process, die right away
if (!o->have_process) {
ondemand_free(o);
return;
}
// set dying
o->dying = 1;
// request process termination if not already
if (!o->process_terminating) {
ondemand_terminate_process(o);
}
}
static void demand_func_new (void *vo, NCDModuleInst *i, const struct NCDModuleInst_new_params *params)
{
struct demand *o = vo;
o->i = i;
// read arguments
if (!NCDVal_ListRead(params->args, 0)) {
ModuleLog(i, BLOG_ERROR, "wrong arity");
goto fail0;
}
// set ondemand
o->od = NCDModuleInst_Backend_GetUser((NCDModuleInst *)params->method_user);
// add to ondemand's demands list
LinkedList1_Append(&o->od->demands_list, &o->demands_list_node);
// start process if needed
if (!o->od->have_process) {
ASSERT(!o->od->dying)
if (!ondemand_start_process(o->od)) {
goto fail1;
}
}
// if process is up, signal up
if (o->od->process_up) {
NCDModuleInst_Backend_Up(i);
}
return;
fail1:
LinkedList1_Remove(&o->od->demands_list, &o->demands_list_node);
fail0:
NCDModuleInst_Backend_DeadError(i);
}
static void demand_free (struct demand *o, int is_error)
{
// remove from ondemand's demands list
LinkedList1_Remove(&o->od->demands_list, &o->demands_list_node);
// request process termination if no longer needed
if (o->od->have_process && !o->od->process_terminating && LinkedList1_IsEmpty(&o->od->demands_list)) {
ondemand_terminate_process(o->od);
}
if (is_error) {
NCDModuleInst_Backend_DeadError(o->i);
} else {
NCDModuleInst_Backend_Dead(o->i);
}
}
static void demand_func_die (void *vo)
{
struct demand *o = vo;
demand_free(o, 0);
}
static int demand_func_getobj (void *vo, NCD_string_id_t objname, NCDObject *out_object)
{
struct demand *o = vo;
ASSERT(o->od->have_process)
ASSERT(o->od->process_up)
return NCDModuleProcess_GetObj(&o->od->process, objname, out_object);
}
static struct NCDModule modules[] = {
{
.type = "ondemand",
.func_new2 = ondemand_func_new,
.func_die = ondemand_func_die,
.alloc_size = sizeof(struct ondemand)
}, {
.type = "ondemand::demand",
.func_new2 = demand_func_new,
.func_die = demand_func_die,
.func_getobj = demand_func_getobj,
.alloc_size = sizeof(struct demand)
}, {
.type = NULL
}
};
const struct NCDModuleGroup ncdmodule_ondemand = {
.modules = modules
};